Unanswered: Stacked columns not stacking

I keep getting my columns to overlap each other instead of stacking. I have "highlight: true" so you can clearly see how multiple columns are overlapping each other.
Another problem (not sure if its related to the stacking problem) is that the colors of each series is displayed the same. I have tried setting the color explicitly in the series loop but they all get the same color always.
Can someone please help me figure out the problem?